One type of semiconductor processing furnace is in the shape of an elongated hollow tube having electric coils wrapped therearound. Replaceable quartz tubes having diameters just slightly less than the internal diameter of the furnace are placed inside the furnaces. One end of the furnace and tube are provided with an opening for a gas injector system for injecting the processing gases into the tube within the furnace during treatment.
Semiconductor wafers are supported within the furnace for processing on an elongated silicon carbide wafer paddle which is defined by an elongated well having upwardly rising and outwardly flaring sides. The wafers are supported vertically on such paddle, typically on wafer cassettes, made of quartz which are mounted on the elongated wafer paddle. Gases are injected into one end of the furnace and flow outwardly through the furnace to treat the wafers, and are exhausted from the opposite furnace end.
One of the concerns associated with processing semiconductor wafers in such furnaces is to provide sufficient exposure of all of the closely stacked wafers to the injected gas. However, the configuration of the furnace in relation to the position of the stacked wafers tends to cause gas to stream down the side of the internal furnace walls, and not uniformly access in between the adjacently stacked wafers. One such method of facilitating injection of gases between the wafers is to provide a baffle in the quartz tube downstream of the injector nozzle to cause turbulence and diffusion. This minimizes the tendency of the gas to stream down the walls of the furnace tube.
This invention concerns another way of increasing the exposure of the wafers to processing gases within such reactor furnaces.